This rule has a lot of qualities as it allows the user to pass both a reporter and an angle (for angles), to draw parallel lines with two wheels attached to the rule, and easily create scales (positive and negative). The plastic which is made the rule is thick enough and flexible not afraid to break it by making it accidentally falling down. What makes an object that there was both strong and effective ... but there is a big problem. I bought this rule mainly to quickly draw parallel lines, yet I quickly realized that my rule deviates from its route after traveling tens of centimeters, and that the lines drawn end up not being parallel to each other. Maybe is it a specific manufacturing defect to my rule ... in any case, I have to remove 2 stars.